Sleep problems are a risk factor for poor physical, emotional, and behavioral health in children and adults (Dahl & El-Sheikh, 2007). The first year of life is an important period for the consolidation and regulation of sleep-wake patterns which have been found to predict sleep patterns later in life. These sleep patterns likely result from intrinsic characteristics of the infant such as temperament (e.g., Carey, 1974) and physiology (e.g., El-Sheikh & Buckhalt, 2005), as well as extrinsic factors such as caregiving (see Sadeh, Tikotzky, & Scher, 2010). Although these factors have been studied independently, the bi-directional and longitudinal relationship between them has not been examined in relation to developing sleep patterns. The current study aims to examine the interplay between caregiving and infant vagal tone (a purported physiological index of self-regulation) in prediction of developing infant sleep patterns over the first six months of life. Due to findings that the abilit to self-regulate at bedtime and through the night is one of the most significant predictors of good sleep quality, we will explore the association between sleep and infant vagal regulation across two contexts: (1) in response to challenge during the day, and (2) at bedtime. We will investigate the moderating role of caregiving behavior during the day and at night and examine the causal relationship between sleep quality and vagal regulation between 3 and 6 months. Finally, due to findings that African American children may have more sleep difficulties than European American children, we will explore these processes in an African American sample. It is important to identify early predictors of sleep patterns in this group, and explore within-group differences, before making between-group comparisons in future studies. The proposed pilot study involves a home visit at 3 and 6 months of age which will include assessments of infant vagal regulation and caregiver-child interactions. Each visit will be followed by 7 days of data collection at bedtime and through the night consisting of objective measures of sleep behavior (actigraphy and video recording) and vagal tone at bedtime. In addition, caregiving behaviors (practices and emotional availability) will be filmed through the night (one time) and mothers will complete a sleep diary by phone each morning. Our current understanding is limited about how various levels of analyses influence sleep development. It is important to move beyond cross-sectional assessments relying on maternal report and identify patterns and trajectories, via objective measurement, that develop during this critical period. Understanding these processes is essential for developing appropriate preventions, or interventions, that will help reduce the prevalence of early sleep problems that may extend into later childhood and beyond.